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Behavior of noncircular tunnels excavated in stratified rock masses-Case of underground coal mines

Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 99-110页

作者： Ngoc Anh Do Daniel Dias Van Diep Dinh Tien Tung Tran Van Canh dao viet doan dao Phuc Nhan Nguyen Department of Underground and Mining Construction.Faculty of Civil Engineering Hanoi University of Mining and Ceology School of Automotive and Transportation Engineering Hefei University of Technology Laboratory 35R Crenoble Alpes University

The amount of tunnels excavated along stratified/sedimentary rock masses in Quangninh coal mine area,vietnam, is gradually increasing. Rock mass in Quangninh is characterized by beddings between rock layers. The behavior of stratified rock masses surrounding the tunnels depends on both the intact rock and the beddings between rock layers. The main characteristics of stratified rock masses that need to be considered are their heterogeneity and anisotropy. Depending on the dip angle of rock layers, movements and failure zones developed surrounding the tunnels can be asymmetrical over the vertical axis of tunnel. This asymmetry causes adverse behaviors of the tunnel structures. The objective of this study is to highlight convergences and yielded zones developed in rock masses surrounding noncircular tunnels in Quangninh coal mine area using a finite element method. The presence of bedding joints is explicitly simulated. The numerical results indicated that with the increase in dip angle of bedding joints, the stress asymmetry over the tunnel vertical axis increases. It gradually leads to an asymmetry of the failure zone surrounding the tunnel. An increase of rock mass quality means a decrease of rock mass sensitivity to the discontinuities. In addition,a dip angle of the bedding joints of approximately 45° could be considered as the critical angle at which the rock mass mechanism changes between sliding and bending.

关键词： Tunnel Bedding Stratification Anisotropic Heterogeneity

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A method for computing unsupported roof distance in roadway advancement and its in-situ application

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International Journal of Mining Science and Technology 2016年第4期26卷 551-556页

作者： Chen Yong Bai Jianbiao Yan Shuai Hao Shengpeng dao viet doan State Key Laboratory of Coal Resource and Safe Mining Key Laboratory of Deep Coal Resource Mining Ministry of Education of China China University of Mining and Technology Xuzhou 22116 China Hanoi University of Mining and Geology Hanoi 10000 Viet Nam

A reasonable unsupported roof distance(URD) when advancing underground coal mine roadways can contribute greatly to safe and rapid roadway development.A mechanical model of the roof,using the relationship between the roof stress distribution and URD,obtained by the difference method,and roof stability according to the in-situ roof stress and rock mass strength was *** subsequently designed a proper range of URD,developed a testing method of URD with the function of mining protection,evaluated roof stability through analyzing the test data and then determined a reasonable *** the factors of the geological conditions,the immediate roof stability and the efficiency of the labor arrangement system,the URD of the advancing roadway of 9802 working face in Zhangshuanglou coal mine was determined to be 6 m using the proposed *** results show that,when a 2 m length of roadway was reinforced by temporary support and high pre-stressed bolt support after the roadway advancement of 6 m per cycle,the speed and the security of the roadway development can be achieved and the advance rate can reach more than 400 m per month.

关键词： Unsupported roof distance (URD)Roadway advancement Difference method Roof stress Drivage per cycle Unsupported roof distance test

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Effect of heating time on structural,morphology,optical,and photocatalytic properties of g-C3N4 nanosheets

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Chinese Physics B 2020年第5期29卷 504-508页

作者： Nguyen Manh Hung Le Thi Mai Oanh Lam Thi Hang Pham Do Chung Pham Thi Duyen dao viet Thang Nguyen Van Minh Center for Nano Science and Technology Hanoi National University of Education136 Xuan Thuy RoadCau Giay DistrictHanoi100000Vietnam Department of Physics Hanoi National University of Education136 Xuan Thuy RoadCau Giay DistrictHanoi100000Vietnam Faculty of Basic Sciences Hanoi University of Natural Resources and Environment41A Phu Dien RoadNorth Tu LiemHanoi100000Vietnam Hanoi University of Mining and Geology Duc Thang wardNorth Tu Liem DistrictHanoi100000Vietnam Military science Academy 322 Le Trong Tan streetDinh CongHoang MaiHanoi100000Vietnam

Effect of heating time on the structural,morphology,optical,and photocatalytic properties of graphitic carbon nitride(g-C3N4)nanosheets prepared at 550℃in Ar atmosphere is *** investigations are carried out by using x-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier-transform infrared spectroscopy(FTIR),UV-vis absorption,and photoluminescence(PL).At a heating temperature of 550℃,g-C3N4 nanocrystals are formed after 0.5 h and become more orderly as the heating time *** surface area of the g-C3N4 nanosheets significantly increases as the preparation time *** g-C3N4 prepared in 2.5 h shows the highest photocatalytic performance,decomposing completely 10 ppm RhB solution under xenon lamp irradiation for 2.0 h.

关键词： nanosheets photocatalytic heating time Ar atmosphere

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Micro Transportation Systems: A Review

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Modern Mechanical Engineering 2011年第2期1卷 31-37页

作者： Phuc Hong Pham Dzung viet dao 不详

This paper summarized and reviewed recent studies of micro transportation systems (MTS) in the MEMS (Micro Electro-Mechanical System) field. Micro transportation systems can be identified and classified into three categories based on the contact types between the objects and the actuators (i.e. liquid-based, solid- based and air-bearing type). Their advantages and disadvantages were also analyzed and compared. The au- thors have proposed and developed three types of solid-based MTS utilizing electrostatic comb-drive actua- tors and ratchet mechanisms to drive the micro container in straight and curved paths. These MTSs have been fabricated with silicon-on-insulator (SOI)-MEMS technology and tested successfully. In the near future, MTSs can be applied in different fields such as medicine (to classify and test blood cells), in bioengineering (to capture, sort and combine bio-cells, DNA), or in micro robot systems.

关键词： Micro Transportation System (MTS) Electrostatic Comb-Drive Actuator (ECA)

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构造应力场中巷道围岩破坏机理研究

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煤矿开采 2014年第2期19卷 13-16,50页

作者：赵红超张东升刘洪林吕金星 dao viet doan 温颖远新疆大学地质与矿业工程学院新疆乌鲁木齐830000 中国矿业大学煤炭资源与安全开采国家重点实验室江苏徐州221008 越南河内矿业地质大学越南河内910000

针对构造应力场中巷道围岩变形破坏基本特征,采用FLAC3D数值计算软件,依次分析侧压系数、内摩擦角、黏聚力对矩形巷道周边应力分布、位移和塑性区扩展的影响。结果表明:侧压系数对巷道围岩变形破坏具有敏感性,随着侧压系数的增大,巷道... 详细信息

针对构造应力场中巷道围岩变形破坏基本特征,采用FLAC3D数值计算软件,依次分析侧压系数、内摩擦角、黏聚力对矩形巷道周边应力分布、位移和塑性区扩展的影响。结果表明:侧压系数对巷道围岩变形破坏具有敏感性,随着侧压系数的增大,巷道两帮移近量呈现正比增加的趋势且明显大于顶底移近量;内摩擦角在一定的取值范围内,与巷道围岩塑性区变化存在着负相关性,但是当其增大到相对的临界点(30°≤φ≤35°)时,塑性区的变化将不再明显;当黏聚力增大到一定程度(C=5.0MPa)时,巷道围岩塑性区的变化将保持在一个相对稳定的水平。在此基础上提出高强让压支护的基本思路,开发了"多孔循环注浆,深浅孔结合"工艺,在工程实践中取得较好效果。

关键词：构造应力围岩侧压系数黏聚力内摩擦角

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Visualization Techniques in Smart Grid

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Smart Grid and Renewable Energy 2012年第3期3卷 175-185页

作者： dao viet Nga Ong Hang See Do Nguyet Quang Chee Yung Xuen Lai Lee Chee Department of Electronics and Communication Engineering Universiti Tenaga Nasional Kejang Malaysia.

Visualization is an established methodology in scientific computing. It has been used in many fields because of its strong capability in large data management and information display. However, its applications in power systems, especially in Smart Grid are still in infancy stage. Besides, while there were a lot of researches working on visualizing data in transmission power system, the study on displaying distribution power system data was limited. Therefore, in this paper, author proposed some techniques to visualize the Smart Grid data at distribution. They are classified in three categories, which are low dimensional techniques, multivariate high dimensional techniques and Geographical Information System (GIS) techniques.

关键词： Smart Grid Visualization Techniques Google Earth GIS QGIS AMI SCADA Spatial Temporal Animation

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Microcystin accumulation and biochemical responses in the edible clam Corbicula leana P. exposed to cyanobacterial crude extract

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Journal of Environmental Sciences 2016年第6期28卷 120-130页

作者： Thanh-Luu Pham Kazuya Shimizu Ayako Kanazawa Yu Gao Thanh-Son dao Motoo Utsumi Graduate School of Life and Environmental Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8572 Japan Faculty of Life Sciences Toyo University Ora-gun Gunma 374-0193 Japan College of Chemical and Environmental Engineering Shandong University of Science and Technology qingdao 266590 China Ho Chi Minh City University of Technology 268 Ly Thuon9 Kiet St. Dist. 10 Ho Chi Mirth City Viet Nam vietnam Academy of Science and Technology （VAST) Institute of Tropical Biology 85 Tran Quoc Toan St. Dist. 3 Ho Chi Minh City Viet Nam

We investigated the accumulation and effects of cyanobacterial crude extract（CCE）containing microcystins（MCs） on the edible clam Corbicula leana P. Toxic effects were evaluated through the activity of antioxidant and detoxification enzymes： catalase（CAT）,superoxide dismutase（SOD）, and glutathione-S-transferases（GSTs） from gills, foot, mantle and remaining soft tissues. Clams were exposed to CCE containing 400 μg MC-LReq/L for10 days and were then kept in toxin-free water for 5 days. Clam accumulated MCs（up to 3.41 ± 0.63 μg/g dry weight（DW） of unbound MC and 0.31 ± 0.013 μg/g DW of covalently bound MC）. Detoxification and antioxidant enzymes in different organs responded differently to CCE during the experiment. The activity of SOD, CAT, and GST in the gills and mantle increased in MC-treated clams. In contrast, CAT and GST activity was significantly inhibited in the foot and mostly only slightly changed in the remaining tissues. The responses of biotransformation, antioxidant enzyme activity to CCE and the fast elimination of MCs during depuration help to explain how the clam can survive for long periods（over a week） during the decay of toxic cyanobacterial blooms in nature.

关键词： Bioaccumulation Cyanotoxins Covalently bound microcystins Aqueous extracts

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Discrete-time sliding mode control with power rate exponential reaching law of a pneumatic artificial muscle system

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Control Theory and Technology 2022年第4期20卷 514-524页

作者： Quy-Thinh dao Trung-Kien Le Tri Van-Anh Nguyen Manh-Linh Nguyen School of Electrical and Electronic Engineering Hanoi University of Science and TechnologyDai Co VietHanoi 11615Vietnam

This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching time and chattering *** proposed method dynamically adapts to the variation of the switching function,which is based on an exponential term and a power rate term of the sliding ***,the controlled system can achieve high tracking performance while still obtain chattering-free ***,the effectiveness of the proposed method is validated through multiple experimental tests,focused on a dual pneumatic artificial muscle ***,experimental results show the effectiveness of the proposed approach in this paper.

关键词： Pneumatic artificial muscle Discrete-time sliding mode control Exponential reaching law Chattering

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Response of laying hens to L-arginine,L-citrulline and guanidinoacetic acid supplementation in reduced protein diet

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Animal Nutrition 2021年第2期7卷 460-471页

作者： Hiep Thi dao Nishchal K.Sharma Emma J.Bradbury Robert A.Swick School of Environmental and Rural Science Faculty of ScienceAgricultureBusiness and LawUniversity of New England2351New South WalesAustralia Faculty of Animal Science Vietnam National University of AgricultureTrau Quy TownGia Lam DistrictHanoiViet Nam Ridley AgriProducts Level 4565 Bourke StreetMelbourneVICAustralia

A study was conducted with Hy-Line Brown laying hens to examine the effects of reduced protein diet,deficiency of arginine(Arg),and addition of crystalline Arg,citrulline(Cit)and guanidinoacetic acid(GAA)as substitutes for *** performance,egg quality,serum uric acid,liver and reproductive organ weights,and energy and protein digestibility were measured using a completely randomized design with 5 *** were a standard diet(17%protein diet;SP),a reduced diet(13%protein diet deficient in Arg;RP)and RP with added Arg(0.35%,RP-Arg),GAA(0.46%equivalent to 0.35%Arg,RP-GAA)or Cit(0.35%,RP-Cit)to the level of *** was hypothesized that performance would decrease with Arg deficient RP diet and the addition of GAA or Cit in RP would allow birds to perform similar or greater than Arg-added RP *** experiment was conducted from 20 to 39 wk of age but the treatment effect was seen only after 29 wk of *** birds offered RP had reduced egg and albumin weights(P0.05).The birds offered RP-GAA decreased FI and egg production(P0.05).However,birds offered the RP-Cit diet tended to have higher Haugh unit(P=0.095)and lower shell breaking strength(P=0.088)compared to all other treatments while those offered RP-GAA had higher energy digestibility(P<0.05)than all other groups but *** limited performance response of hens fed RP with added Arg,GAA,or Cit may be due to deficiency of some other nutrients in RP such as phenylalanine,potassium or non-essential amino acids and other components of soybean meal in the diet.

关键词： Arginine Citrulline Guanidinoacetic acid Laying hen Reduced protein

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Influence of sintering behavior on the microstructure and electrical properties of BaTiO_(3) lead-free ceramics from hydrothermal synthesized precursor nanoparticles

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Journal of Advanced Dielectrics 2021年第2期11卷 42-51页

作者： Do viet On Le Dai Vuong Truong Van Chuong dao Anh Quang Ho Van Tuyen Vo Thanh Tung Department of Physics College of Sciences Hue UniversityHue CityVietnam Faculty of Chemical and Environmental Engineering Hue Industrial College Hue CityVietnam Institute of Research and Development Duy Tan University Da Nang CityVietnam Faculty of Natural Sciences Duy Tan University Da Nang CityVietnam

BaTiO_(3) nanoparticles were synthesized by hydrothermal method using amorphous phase TiO_(2) precursor as the *** microstructure and phase structure were determined using XRD,SEM and Raman spectroscopy analysis *** results showed that BaTiO_(3) nanoparticles have tetragonal structure,average size of about 100 nm was obtained at Ba/Ti ratio of 1.5,synthesis temperature of 200℃ and reaction time of 12 *** components of the BaTiO_(3) lead-free ceramic system are fabricated by conventional solid-phase reaction from the average size BaTiO_(3) particles about 100 nm obtained by hydrothermal *** effects of sintering behavior on dielectric,ferroelectric and piezoelectric properties of BT high-density ceramic were *** BaTiO_(3) ceramic composition sintered at 1300℃ has a relative density of 97%,the value of the electromechanical coefficient kp=0.40,k33=0.42,the large piezoelectric coefficient d_(33)=300 pC/N,d_(31)=−125 pC/N.

关键词： BaTiO_(3)nanoparticles lead-free ceramics piezoelectric ferroelectric properties

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